Data storage and retrieval systems are used to store information provided by one or more host computer systems. Such data storage and retrieval systems receive requests to write information to one or more secondary storage devices, and requests to retrieve information from those one or more secondary storage devices. Upon receipt of write request, the system stores information received from a host computer in a data cache. In certain implementations, a copy of that information is also stored in a nonvolatile storage device. Upon receipt of a read request, the system recalls information from the one or more secondary storage devices and moves that information to the data cache. Thus, the system is continuously moving information to and from storage devices, and to and from the data cache.
Many data processing applications require what is sometimes referred to as “24/7/365” operational capabilities, i.e. the data storage and retrieval systems are optimally continuously in operation. In order to provide such “24/7/365” operational capabilities, some information storage and retrieval systems comprise multiple clusters. What is needed is a method to provide failover protection in a multi-cluster information storage and retrieval system after the failure of one cluster and after the subsequent failure of a device adapter disposed in the operational cluster.